window.onload = function(){
	imgLocation("container","box");
	
	var imgData = {"data":[{"src":"2.jpg"},{"src":"3.jpg"},{"src":"4.jpg"},{"src":"5.jpg"},{"src":"6.jpg"}]}
	window.onscroll = function(){
		if(checkFlag()){
			var cparent = document.getElementById("container");
			for(var i = 0; i < imgData.data.length; i++){
				var ccontent = document.createElement("div");
				ccontent.className = "box";
				cparent.appendChild(ccontent);
				var boximg = document.createElement("div");
				boximg.className = "box_img";
				ccontent.appendChild(boximg);
				var img = document.createElement("img");
				img.src = "img/" + imgData.data[i].src;
				boximg.appendChild(img);
			}
			imgLocation("container","box")
		}
	}
}
function checkFlag(){
	var cparent = document.getElementById("container");
	var ccontent = getChildElement(cparent,"box");
	var lastContentHeight = ccontent[ccontent.length - 1].offsetTop;
	var scrollTop = document.documentElement.scrollTop||document.body.scrollTop;
	var pageHeight = document.documentElement.clientHeight||document.body.clientHeight;
	if(lastContentHeight < scrollTop + pageHeight){
		return true;
	}
}
function imgLocation(parent,content){
//	将parent下所有的conten全部取出
	var cparent = document.getElementById(parent);
	var ccontent = getChildElement(cparent,content);
	var imgWidth = ccontent[0].offsetWidth;
	var num = Math.floor(document.documentElement.clientWidth / imgWidth);
	cparent.style.cssText = "width:" + imgWidth * num + "px;margin: 0 auto";
	
	var BoxHeightArr = [];
	for(var i = 0; i < ccontent.length; i++){
		if(i < num){
			BoxHeightArr[i] = ccontent[i].offsetHeight;
		}else{
			var minheight = Math.min.apply(null,BoxHeightArr);
			var minIndex = getminheightLocation(BoxHeightArr,minheight);
			ccontent[i].style.position = "absolute";
			ccontent[i].style.left = ccontent[minIndex].offsetLeft + "px";
			ccontent[i].style.top = minheight + "px";
			BoxHeightArr[minIndex] += ccontent[i].offsetHeight;
		}
	}
}
function getminheightLocation(BoxHeightArr,minHeight){
	for(var i in BoxHeightArr){
		if(BoxHeightArr[i] == minHeight){
			return i;
		}
	}
}
function getChildElement(parent,content){
	var contentArr = [];
	var allcontent = parent.getElementsByTagName("*");
	for(var i = 0; i < allcontent.length; i++){
		if(allcontent[i].className == content){
			contentArr.push(allcontent[i]);
		}
	}
	return contentArr;
}
